Mineral oil compositions of suppressed foaming tendency



Patented June 29, I954 U srAr ENT OFFICE MINERAL OIL COMPOSITIONS F SUP- PRESSED FOAMING TENDENCY N 0 Drawing. Application May 8, 1951, Serial No. 225,268

13 Claims.

This invention relates to new mineral oil compositions containing foam depressing agents.

Mineral oils have a tendency to foam or froth when agitated in the presence of gases, particularly when compounded as lubricatin compositions. The additives found desirable for the proper functioning of the lubricant frequently enhance the tendency to foam. The amount and character of the foam varies with the composition and external conditions, in some instances being so severe as to seriously interfere with the use of the composition. For example under some conditions the volume of foam produced may be several times that of the original oil composition.

The esters of phosphorus acids are recognized as a desirable class of additives in the compounding of lubricating oil compositions. They may serve as antioxidants, corrosion inhibitors, antiwear agents and extreme pressure agents and other functions. An unusually wide variety of esters of phosphorus acids have been suggested for various purposes. However, some of these esters enhance the foamin tendencies of the oil or interfere with the suppression of foam. The addition of various materials to suppress foaming tendencies is known but many otherwise efficient foam inhibitors fail to function in the p ence of certain esters of phosphorus acids, particularly acid esters. Thus, the search for satisfactory foam inhibitors is complicated by the fact that the result in the blank oil does not mean that the same or even similar results will be obtained with a compounded oil. Furthermore, compounds which are ineffective in the blank oil may have useful foam suppressing properties in the final composition.

An object of this invention is to provide compositions of suppressed foaming characteristics.

Another object is to provide a composition comprising mineral oil and one or more alkaryl esters of phosphorus acids of suppressed foam characteristics.

A further object is to provide new anti-foaming agents effective when dispersed in small amounts into lubricants compounded with alkaryl esters of phosphorus acids. Still another object is to provide anti-foamin agents which are effective in the presence of halogen and sulfur compounds. Another object is to provide anti-foaming agents which may be added to a concentrate consisting either in an admixture of additives including an alkaryl ester of a phosphorus acid or a concentrated oil solution and the normal foaming properties of the mineral oil lubricants compounded from the concentrate thereby reduced.

Other and further objects will be apparent from the detailed description and explanation followmg.

In accordance with this invention it has been discovered that amides of lower aliphatic carboxylic acids are effective for suppressing the foaming of mineral oil compositions containing alkaryl esters of phosphorus acids. By lower aliphatic carboxylic acids are meant acids containing from one to four carbon atoms or in other words formic through butyric acids. The amide group may be unsubstituted or substituted by one or more alkyl groups, as for example methyl, ethyl, isopropyl or butyl groups. Very small amounts based on the total composition are sufiicient in most cases. Thus, the general useful range is from 9.001% to 1.0% and usually amounts within the range of 0.005 to 0.05% are preferred.

Phosphorus esters in which the ester forming constituent comprises at least one alkylated aryl group and especially the acid esters have been found to interfere with the foam suppressing properties of many otherwise efficient inhibitors. This type additive is often used in compounding heavy duty gear oil lubricants and the amides of this invention are especially adapted for use in con unction with the alkaryl acid esters of phosphorus. Examples of Dh D -S ester additives are ortho-n-butyl phenyl phosphate, and phosphite, ortho-tert. butyl phenyl phosphate and phosphite, 2,4-cli-tert. butyl phenyl phosphate and phosphite, ortho-isoarnyl phenyl phosphate and phosphite, ortho-tert. ainyl phenyl phosphate and phosphite, 2,4,6-tri-tert. butyl phenyl phosphate, 2,6--di-tert. butyli-methyl phenyl phos- 'phate, hexylphenylphosphate, heptylphenylphosphate, octylphenylphosphate, dodecyiphenylphosphate and dioctylphenylp-hosphate. The mixture of acid esters obtained by reaction of P205 and an alkylated phenol may be used to advantage.

The relative effectiveness of the amides of lower carboxylic acids in preventin foaming of mineral oil compositions may be demonstrated by a test in which the composition is aerated under controlled conditions. In this test an approximately ml. sample of the oil composition is placed in a 1000 ml. graduated cylinder containing a diffuser stone of such size that the oil level rises to the 200 m1. mart: and air in the form of fine bubbles is passed upwardly through the column of the composition. The air is blown through the diffuser for '5 minutes at the rate-of 0.2 cubic foot 3 per hour. The air is then shut off and the volume of foam recorded. After an interval of 10 minutes, the volume of foam is again recorded. If the foam collapses to zero before the expiration of 10 minutes, the actual time required for complete disappearance of foam is noted.

As illustrative of the invention heavy duty gear oil lubricating compositions were compounded from an S. A. E. 30 Pennsylvania grade base as follows:

4 cient to decrease the normal foaming properties of the composition.

2. A mineral lubricating oil composition comprising a major proportion of a hydrocarbon oil containing a small amount of an acid alkaryl phosphate and an amide of an aliphatic carboxylio acid containing less than five carbon atoms in small amount sufficient to decrease the normal foaming properties of the composition.

3. A mineral lubricating oil composition com- Compositlon A B C D E Base oil parts by Weight" 100 100 100 100 100 Reaction product of chlorinated kerosene and potassium isopropyl xanthate parts by weight" 5 5 5 5 Dihydroabietyl maleate .dol 1 1 l Reaction product of di-tert. amylphenol and P305 "parts by weight 0. 5 0. 5 0.37 Reaction product of mono-tort. octylphenol and PzO5. parts by weight 0. 5 Reaction product of mono nonylphenol and P205 "parts by weight 0. 5 Chlorinated wax .d 4. Suliurized terpene do l- 1.2

The foaming characteristics of the compositions prising a major proportion of a hydrocarbon oil so prepared were determined by the method decontaining a small amount of an acid alkaryl scribed and compared to those of the same comphosphate and dimethyl formamide in small positions containing a small amount of dimethyl amount sufficient to decrease the normal foamformamide. ing properties of the composition.

4. A mineral lubricating oil composition com- Inmbitor Foaming ML after 19 prising a major proportion of a hydrocarbon oil composition Pam's by mitialRead. ig gf ggg ig containin a small amount of an ac1d alkaryl Welght 1111- Zem phosphate and (111118511371 acetamide in small amount sufilcient to decrease the normal foaming" A none 600 200. properties of the composition.

3 g: 8g 5. A mineral lubricating oil composition com- 0.01 so 20sec. prising a major proportion of a hydrocarbon oil g containing a small amount of an acid alkaryl none 460 15. I phosphate and acetamide in small amount suffigg 2% i cient to decrease the normal foamin properties 0.02 52 35 sec of the composition.

6. A mineral lubricating oil composition com- 1; W111 be noted that t presence of u prising a major proportion of a hydrocarbon oil amount of dimethyl formamide markedly reduced c nt ining a small amount of diamylp yl acid the foaming and that the small volume of foam phosphate d im hyl form mid in m l hi was formed disappeared ithi t i amount sufficient to decrease the normal foaming utes. Acetamide, formamide and dimethyl acetpr p r s f h mp i n. amide were tested under similar conditions and '7. A mineral lubricating oil composition comfound to be efficient foam inhibitors. Excellent p g major D p t n f a hydrocarbon 011 results have been obtained with inhibitors of the i ng a ll m n of m n y ph Structure acid phosphate and dimethyl formamide in small 0 R1 amount sufiicient to decrease the normal foamg ing properties of the composition. 8. A mineral lubricating oil composition com- R2 prising a major proportion of a hydrocarbon oil where R, R1 and R2 are selected f hydrogen containing a small amount of monononylphenyl and allryl groups less than four carbon atoms. a191d p p ate and dimeth l formamide in small The foamfiuppressing amide may be added to amount suhlcient to decrease the normal foamthe alkaryl phosphorus ester additive, to an admg proportles 0f e composit on. mixture of the ester and other compounding 9. A mineral lubricating O11 composition comagents for mineral oil lubricants, to a concenprising major p opo ion Of a hydrocarbon oil trated acid solution of one or more mineral oil contammg Small-amount of dlbutrlrhonyl acld adjuvants or to the compounded lubricant. For PhOsphate and dlmethyl formamlde 111 Small example it is convenient to add the amide to the amount sufficient to decltetlse the normal foaming admixtures described above as compositions A, B, propertles of the composltlon- C, D and E but omitting the base oil. Fr such 10. A mineral lubricating oil composition comconcentrates mineral oil lubricants of decreased prising a major PYGDOTUOTI Of a hydrocarbon 011, fo mi tendencies are readily produce minor proportion of an organic E. P. additive w is claimedis; containing both halogen and sulfur, a minor 1. A mineral lubricating oil composition comproportion f an lk ryl acid phosphate containprjsing a major proportion of a hydrocarbon at least 4: carbon atOmS the Side chain and containing a Small amount of an alkaryl phos a small amount of an amide of a lower aliphatic phorus ester additive d an amide of a lower carboxylic acid sufiicient to decrease the normal foaming properties of the composition.

aliphatic carboxylic acid in small amount suffi- 11. A mineral lubricating oil composition comprising a major proportion of a hydrocarbon oil containing minor proportions of E. P. additives having in chemical combination sulfur and chlorine, a minor proportion of an alkaryl acid phosphate containing at least 4 carbon atoms in the side chain and a small amount sufficient to decrease the normal foaming properties of the composition of an amide of the structure where R, R1 and R2 are selected from hydrogen and alkyl groups of less than 4 carbon atoms.

12. A mineral lubricating oil composition comprisin a major proportion of a hydrocarbon oil containin a small amount of an acid alkaryl phosphate and a small amount of formamide sufficient to decrease the normal foaming properties of the composition.

where R, R1 and R2 are selected from hydrogen and alkyl groups of less than 4 carbon atoms.

No references cited. 

1. A MINERAL LUBRIACTING OIL COMPOSITON COMPRISING A MAJOR PROPORTION OF A HYDROCARBON OIL CONTAINING A SMALL AMOUNT OF AN ALKARYL PHOSPHORUS ESTER ADDITIVE AND AN AMIDE OF A LOWER ALIPHATIC CARBOXYLIC ACID IN SMALL AMOUNT SUFFICIENT TO DECREASE THE NORMAL FOAMING PROPERTIES OF THE COMPOSITION. 